One thing you learn when dealing with sustainability is to take a broad view. Without that, you may miss something and, for example, adopt a technology that has an indirect unwanted effect. You also learn that conservation of materials and energy as a first principle has a multiplier effect that is hard to beat. For example, everybody is concerned about gasoline prices and some argue we should get electric cars which would be much more efficient. We also have a bit of a water problem in Atlanta and we all have been dutifully limiting our water use. Our lack of water is often cited by opponents of ethanol fuels. Recently, one “expert” opposed to producing ethanol claimed that “ethanol requires in excess of 3 gallons of water to be produced” (I even read 5 gallons recently). Yes, but is that water USE or CONSUMPTION? There is a BIG difference depending on how you define use and/or consumption. Ethanol production is a process that requires water (like paper production also requires water). But that water is separated from the ethanol using distillation and that water vapor can be re-condensed into pure water for reuse. There is always some loss, but losing it all would be a dumb process.

The same “expert” said that electric cars would be a much better investment. Seemingly, the issue of electric cars and water are totally unrelated. But perhaps you may have read somewhere that limiting water releases from Lake Lanier would cause some problems for power plants in Florida. Why is that? Well, most power plants (except hydro plants) use heat to generate steam to run turbines that have a big alternator on them to generate electricity. And where there is heat, there is typically cooling. To get an idea how much, go to www.georgiapower.com/about/brochures.asp and click on the Georgia Power Plant Bowen Brochure. You will read that the plant has four cooling towers and “Each cooling tower circulates more than 285,000 gallons of water per minute; 2.5 percent evaporates and is seen as water vapor rising from the cooling towers.” It is important to note the difference in numbers. I could say that Georgia Power’s Bowen Plant uses 4 x 285,000 = 1.14 MILLION gallons of water per minute. To put this in perspective that is the equivalent of 400,000 residents of the City of Atlanta flushing their toilet almost every minute!

But that is misleading.

In reality “only” 28,500 gallons per minute evaporates because the rest is recaptured in their closed loop system. That’s much better right? Well, to put 28,500 gallons in perspective, it means that every minute an empty residential swimming pool is completely (re)filled with water…

Water consumption for generating electricity in Plant Bowen is about half a gallon per kilowatt-hour of electricity (which according to some is a bit optimistic – typical consumptions may be near 0.7 gallons per kWh). So the next time you switch on the light or use electricity in Atlanta, remember it also costs water.